As a trolley-type truck of this kind, one shown in Japanese Patent Application Laid-Open No. S63-35102 (Patent Literature 1) and the like can be cited.
In the trolley-type truck of Patent Literature 1, a dump truck used for ore transportation in a large-scale mine is described, and it is described that the dump truck travels by a generator driven by an engine in the non-trolley mode, and travels by external electric power by collecting electricity through a double-track type overhead wire by a pair of pantographs mounted on the truck in the trolley mode. Also, in the Patent Literature, an invention is described in which the pantograph is immediately descended when the pantograph deviates from the overhead wire.